System for controlling lift path of machine work tool

ABSTRACT

A skid steer loader including a linkage actuation system and a control system for controlling a lift path of a work tool is disclosed. The linkage actuation system includes a first arm, a second arm, and the work tool to contact a work surface. The control system includes a first actuator between a frame and the first arm, a second actuator between the first arm and the second arm, and a third actuator between the second arm and the work tool, for moving the first arm, the second arm, and the work tool about a first pivotal axis, a second pivotal axis, and a third pivotal axis, respectively. The controller controls the actuation of two of the first actuator, the second actuator, and the third actuator for moving the work tool along a lift path, from a plurality of lift paths, based on an operator&#39;s selection.

TECHNICAL FIELD

The present disclosure relates to a skid steer loader, and more specifically to a system for controlling a lift path of a work tool of the skid steer loader.

BACKGROUND

Typically, work machines, such as skid steer loaders are used for raising, lifting, carrying, and pushing objects. A skid steer loader includes a frame, a link arm assembly connected to the frame, and a work tool coupled to the link arm assembly. The work tool may include, but is not limited to a bucket, a forklift, and a grapple. Usually, each skid steer loader is adapted to include a single lift path for the work tool, i.e., the work tool can follow a single lift path for performing operations. Therefore, flexibility of the skid steer loader, in terms of lift paths that can be followed by the work tool, is limited. This in turn would limit the variety of operations that can be performed by the skid steer loader. For example, at a construction worksite, multiple operations ranging across a wide variety are performed. Since each skid steer loader is limited to a single lift path of the work tool, multiple skid steer loaders have to be employed for accomplishing the variety of operations, which would result into a high cost of operation at the work site. Also, the operator may face difficulty while managing the operations by using the single lift path only. Moreover, owing to the limited movement of the work tool, the quality of the operations is undesirably dependent on the skill set of the operator.

U.S. Pat. No. 2,775,356, hereinafter referred to as ‘356, describes a front-end-loading portable power shovel. The power shovel includes a power-propellable frame and a pair of lift-arms arranged on opposite sides of the frame and having their rear ends pivoted to the frame for up and down movement. The power shovel also includes a pair of hydraulic cylinder-assemblies operatively interposed between the frame and the lift-arms. The power shovel includes forward extension-arms pivotally connected to the lift-arms for up and down movement. The power shovel also includes a pair of hydraulic cylinder-assemblies operatively interposed between the lift-arms and the extension-arms. The power shovel further includes a shovel having its rearward portion pivotally connected to the forward ends of the extension-arms, and a hydraulic cylinder-assembly operatively inter-posed between the shovel and the extension-arms. The first pair of hydraulic cylinder-assemblies and the second pair of hydraulic cylinder-assemblies are operable independently of each other. The hydraulic cylinder assembly intermediate the shovel and the extension-arms is operable independently of the first two pairs of hydraulic cylinder assemblies. However, the ‘356 patent offers a complicated and expensive structure with a high number of components.

SUMMARY OF THE DISCLOSURE

In one aspect of the present disclosure, a skid steer loader is provided. The skid steer loader includes a frame, a linkage actuation system, and a control system. The linkage actuation system includes a first arm connected to the frame, a second arm coupled to the first arm, and a work tool coupled to the second arm. The work tool is adapted to contact with a work surface to perform an earth moving operation. The control system controls a lift path of the work tool of the linkage actuation system. The control system includes a first actuator, a second actuator, a third actuator, and a controller. The first actuator is coupled between the frame and the first arm, and is adapted to move the first arm about a first pivotal axis. The second actuator is coupled between the first arm and the second arm, and is adapted to move the second arm about a second pivotal axis. The third actuator is coupled between the second arm and the work tool, and is adapted to move the work tool about a third pivotal axis. The controller is in communication with the first actuator, the second actuator, and the third actuator. The controller is adapted to receive an input from an operator. The input is indicative of a selection of the lift path, from a plurality of predefined lift paths. The controller is adapted to control the actuation of two of the first actuator, the second actuator, and the third actuator for moving the work tool along the selected lift path.

Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a skid steer loader with a control system for controlling a lift path of a work tool, according to concepts of the present disclosure;

FIG. 2 is a schematic view of a linkage actuation system for an implement of the skid steer loader moving the work tool from a first position to a second position along a lift path, according to concepts of the present disclosure;

FIG. 3 is a partial perspective view of the linkage actuation system along with a partial schematic view of a control system for controlling the linkage actuation system of the skid steer loader, according to concepts of the present disclosure;

FIG. 4 is an exemplary list of predefined lift paths for the work tool, according to concepts of the present disclosure; and

FIG. 5 is a flow chart depicting a method of controlling the lift path of the work tool, according to concepts of the present disclosure.

DETAILED DESCRIPTION

Wherever possible, the same reference numbers will be used throughout the drawings to refer to same or like parts. Moreover, references to various elements described herein are made collectively or individually when there may be more than one element of the same type. However, such references are merely exemplary in nature. Any reference to elements in the singular is also to be construed to relate to the plural and vice-versa without limiting the scope of the disclosure to the exact number or type of such elements unless set forth explicitly.

FIG. 1 shows a side view of a skid steer loader 10 with a control system 12 for controlling a lift path of a work tool 14 (shown in FIG. 2), according to one embodiment of the present disclosure. The skid steer loader 10 includes a frame 16, a number of ground engaging members 18 for propelling the skid steer loader 10, a linkage actuation system 20 coupled to the frame 16, the control system 12 coupled between the frame 16 and the linkage actuation system 20, and an operator station 22 for accommodating an operator. The ground engaging members 18 are in contact with a ground surface 24 for moving the skid steer loader 10 on the ground surface 24. The ground engaging members 18 include a set of wheels disposed each at a front end 26 and a rear end 28 of the skid steer loader 10.

The linkage actuation system 20 is coupled to the frame 16 near the rear end 28 by a first pivotal connection 30. The linkage actuation system 20 includes a first arm 32 coupled to the frame 16 by the first pivotal connection 30, a second arm 34 coupled to the first arm 32 by a second pivotal connection 36, and the work tool 14 coupled to the second arm 34 by a third pivotal connection 38. The first arm 32 and the second arm 34 support the work tool 14 for operations, such as lifting, carrying, and pushing objects. The linkage actuation system 20 also includes a support member 40 mounted on the first arm 32 for supporting the components of the control system 12.

For controlling the movement of the linkage actuation system 20, the control system 12 is coupled between the frame 16 and the linkage actuation system 20. The control system 12 is coupled to the frame 16 near the rear end 28 by a fourth pivotal connection 42. The control system 12 includes a first actuator 44, a second actuator 46, a third actuator 48 (shown in FIG. 3), and a controller 50 (shown in FIG. 3) in communication with the first actuator 44, the second actuator 46, and the third actuator 48.

The first actuator 44 is coupled between the frame 16 and the first arm 32. At one end, the first actuator 44 is coupled to the frame 16 by the fourth pivotal connection 42. At another end, the first actuator 44 is coupled to the first arm 32 through a fifth pivotal connection 52 on the support member 40 mounted on the first arm 32. The second actuator 46 is coupled between the first arm 32 and the second arm 34. At one end, the second actuator 46 is coupled to the first arm 32 through a sixth pivotal connection 54 on the support member 40. At another end, the second actuator 46 is coupled to the second arm 34 through a fixed connection 56. The third actuator 48 is coupled between the second arm 34 and the work tool 14. The first actuator 44, the second actuator 46, and the third actuator 48 are hydraulic actuators, and are powered by a hydraulic system 58 disposed in the skid steer loader 10.

The skid steer loader 10 further includes an engine (not shown) enclosed in an engine compartment 60 to provide power to a main drive system (not shown) and the linkage actuation system 20 for moving the skid steer loader 10 and the work tool 14, respectively. The engine compartment 60 is disposed near the rear end 28 of the skid steer loader 10. In an example, the engine may produce a mechanical power output or an electrical power output that may further be converted to a hydraulic power for moving the linkage actuation system 20.

The operator station 22 accommodates the operator to control operations of the skid steer loader 10 and the control system 12. The operator station 22 includes a plurality of control equipment (not shown) for the operator to control the operations of the skid steer loader 10.

FIG. 2 shows a schematic view of the linkage actuation system 20 for an implement of the skid steer loader 10 moving the work tool 14 from a first position to a second position along the lift path. The first position is referred to as a position of the work tool 14, when the work tool 14 is near the ground surface 24. The second position is referred to as a position of the work tool 14, when the work tool 14 is in an elevated position away from the ground surface 24. In one example, the operator moves the work tool 14 from the ground surface 24 to a maximum height in such a manner that a defined point of the work tool 14 travels along the lift path. For moving the work tool 14 from the first position to the second position, the first arm 32 moves about the first pivotal connection 30 in an upward direction.

FIG. 3 shows a partial perspective view of the linkage actuation system 20 along with a partial schematic view of the control system 12 for controlling the linkage actuation system 20 of the skid steer loader 10. The support member 40 supports the first actuator 44 and the second actuator 46 on the first arm 32 of the linkage actuation system 20. The first actuator 44 is a first pair of hydraulic actuators that is connected to the support member 40 through the fifth pivotal connection 52. Similarly, the second actuator 46 and the third actuator 48 are a second and a third pair of hydraulic actuators, respectively. Each of the hydraulic actuators includes a cylinder and a piston disposed within the cylinder. The piston reciprocates within the cylinder for controlling the lift path of the work tool 14.

The first actuator 44 moves the first arm 32 of the linkage actuation system 20 about a first pivotal axis AA′. When the controller 50 actuates the first actuator 44, i.e., the first pair of hydraulic cylinders, the pistons of the first pair of hydraulic cylinders extend out of the cylinders and move the first arm 32 about the first pivotal axis AA′ defined by the first pivotal connection 30. The movement of the first arm 32 is translated to the second arm 34 and eventually to the work tool 14. Consequently, the work tool 14 moves about the first pivotal axis AA′.

The second actuator 46 moves the second arm 34 of the linkage actuation system 20 about a second pivotal axis BB′. The second pair of hydraulic actuators is disposed along the length of the first arm 32. When the controller 50 actuates the second actuator 46, i.e., the second pair of hydraulic cylinders, the pistons of the second pair of hydraulic actuators extend out of the cylinders and move the second arm 34 about the second pivotal axis BB′ defined by the second pivotal connection 36. The movement of the second arm 34 is translated to the work tool 14. Consequently, the work tool 14 moves about the second pivotal axis BB′.

The third actuator 48 moves the work tool 14 about a third pivotal axis CC′. The third pair of hydraulic actuators is disposed in such a manner that an extension and retraction of the pistons move the work tool 14 about the third pivotal axis CC′ defined by the third pivotal connection 38. The third actuator 48 pivots the work tool 14 relative to the second arm 34 for dumping, leveling or curling the work tool 14. Therefore, the first actuator 44, the second actuator 46, and the third actuator 48 move the first arm 32, the second arm 34, and the work tool 14 about the first pivotal axis AA′, the second pivotal axis BB′, and the third pivotal axis CC′, respectively.

In order to move the work tool 14 along a lift path, the controller 50 receives an input from the operator. The control system 12 includes a plurality of predefined lift paths for the work tool 14. The input is indicative of a selection of one of the predefined lift paths by the operator. For providing the input to the controller 50, the operator station 22 includes a dashboard with a number of buttons allotted for the selection of the predefined lift paths. Actuation of each button would transmit a signal to the controller 50 indicating a selection of a predefined lift path by the operator. Based on the input, the controller 50 actuates two of the first actuator 44, the second actuator 46, and the third actuator 48 so as to move the work tool 14 along the selected lift path. The controller 50 electronically actuates two of the first actuator 44, the second actuator 46, and the third actuator 48. The actuator that is not electronically actuated by the controller 50 is then actuated manually by the operator. For example, in case the operator actuates the first actuator 44, the controller 50 actuates the second actuator 46 and the third actuator 48. In another example, in case the operator actuates the second actuator 46, the controller 50 actuates the first actuator 44 and the third actuator 48. Similarly, when the operator actuates the third actuator 48, the controller 50 actuates the first actuator 44 and the second actuator 46. Therefore, the operator manually controls or actuates one of the first actuator 44, the second actuator 46, and the third actuator 48; whereas the controller 50 electronically controls the other two actuators for moving the work tool 14 along the selected lift path. Further, in one example, the control system 12 may control the actuators based on an angular orientation of the first arm 32, the second arm 34, and the work tool 14.

FIG. 4 shows an exemplary list of the plurality of the predefined lift paths for the work tool 14. As shown in the exemplary list, the predefined lift paths include a fuel efficient lift path, a maximize tip capacity path, a maximize height path, a maximize reach path, a vertical lift path, a horizontal reach path, and a user defined path. The exemplary list also includes an exemplary lift path followed by the work tool 14 against each of the predefined lift paths. The predefined lift paths are not limited to the lift paths shown in the exemplary list.

The fuel efficient lift path is indicative of a lift path that optimizes the consumption of fuel while the work tool 14 follows the lift path. The maximize tip capacity path is indicative of a lift path that allows the work tool 14 to achieve the maximum tip capacity while following the lift path. The maximize height path is indicative of a lift path that allows the work tool 14 to achieve the maximum height while following the lift path. The maximize reach path is indicative of a lift path that allows the work tool 14 to sweep the maximum area while following the lift path. The vertical lift path is indicative of a lift path that allows the work tool 14 to follow a path in a vertical direction without making any movement in a horizontal direction. The horizontal reach path is indicative of a lift path that allows the work tool 14 to move in the horizontal direction without making any movement in the vertical direction.

When the user defined path is selected by the operator, the work tool 14 follows a lift path that is defined and saved by the operator in the control system 12. In order to enable the user defined path, the operator defines a lift path by moving the linkage actuation system 20 and the control system 12 manually. Therefore, the operator makes the work tool 14 move along a lift path that is then saved in the control system 12 as the user defined path. The operator then moves the work tool 14 along the saved lift path by selecting the user desired path.

In one example, the operator may control two of the first actuator 44, the second actuator 46, and the third actuator 48. In such a case, the controller 50 may then actuate the actuator that is not controlled or actuated by the operator. Therefore, the controller 50 may actuate one of the first actuator 44, the second actuator 46, and the third actuator 48 that is not being manually controlled.

In one example, the skid steer loader 10 may be replaced with any machine that includes the work tool 14 for performing an operation, without departing from the scope of the present disclosure. Such machines may include, but are not limited to, a mobile machine that performs operations associated with an industry, such as mining, construction, farming, transportation, or any other industry known in the art.

The work tool 14 may include, but is not limited to, a dirt bucket, a utility bucket, a multi-purpose bucket, a pallet fork, a utility grapple bucket, a light material bucket, a utility fork, an industrial grapple bucket, an industrial grapple fork, an angle blade, an auger, a broom, a cold planer, a hydraulic hammer, a landscape rake, a landscape tiller, a material handling arm, a stump grinder, a trencher, and a vibratory compactor.

In one example, the ground engaging members 18 may include a set of endless tracks for propelling the skid steer loader 10. In another example, the ground engaging members 18 may include a combination of wheels and endless tracks.

In one example, the controller 50 of the control system 12 may electronically actuate one of the first actuator 44, the second actuator 46, and the third actuator 48. The two actuators that are not actuated by the control system 12 may then be controlled manually by the operator. In another example, the control system 12 may electronically actuate the first actuator 44, the second actuator 46, and the third actuator 48.

In one example, the operator may select a predefined lift path for moving the linkage actuation system 20 to a desired position and may then switch to another predefined lift path for performing an operation. For example, the operator may select the vertical lift path for moving the work tool 14 to a desired height. When the work tool 14 reaches the desired height, the operator may select the horizontal reach lift path for extending the work tool 14 to a desired position at the desired height.

In one example, the engine may be an internal combustion engine that runs on fuels, such as diesel, gasoline, gaseous fuels, or any other type of fuel known in the art. In one example, the mechanical power output or the electrical power output may be converted to a pneumatic power for actuating the linkage actuation system 20.

The operator station 22 may include a number of control equipment (not shown) for the operator to control the operations of the skid steer loader 10. The number of control equipment may include, but is not limited to, control levers, display devices for displaying information to the operator, and an electronic system for allowing the operator to electronically control various systems/components of the skid steer loader 10, such as the engine, the linkage actuation system 20, and the control system 12.

INDUSTRIAL APPLICABILITY

The present disclosure relates to the skid steer loader 10 with the control system 12. The control system 12 controls the lift path of the work tool 14 of the linkage actuation system 20 of the skid steer loader 10. The control system 12 offers the plurality of predefined lift paths for the work tool 14 to the operator. Upon selection of a lift path, from the predefined lift paths, the control system 12 controls the actuation of two of the first actuator 44, the second actuator 46, and the third actuator 48 for moving the linkage actuation system 20 and therefore, the work tool 14 along the selected lift path.

FIG. 5 shows a flow chart depicting a method 62 of controlling the lift path of the work tool 14. At step 64, the method 62 includes receiving the signal being indicative of a selection of a lift path, from the predefined lift paths. The controller 50 receives the signal from the operator. At step 66, upon receiving the signal, actuation of two of the first actuator 44, the second actuator 46, and the third actuator 48 is controlled. The actuation is controlled so as to move the work tool 14 along the selected lift path. The controller 50 controls the actuation of two of the first actuator 44, the second actuator 46, and the third actuator 48. The actuator that is not controlled by the controller 50 is controlled by the operator.

With the present disclosure, the control system 12 of the skid steer loader 10 offers multiple lift paths for the work tool 14. The wide variety of predefined lift paths offered by the control system 12 reduces the efforts of the operator to define a new lift path for each operation. Further, the user defined lift path would allow the operator to modify or devise a lift path based on an operation to be performed. This would provide flexibility to the skid steer loader 10 and the work tool 14 for performing a variety of operations. Also, the electronic actuation of two of the first actuator 44, the second actuator 46, and the third actuator 48 offers a simple and convenient control of the linkage actuation system 20 and therefore, of the work tool 14. Also, the extent of dependency of the quality of an operation on the skill set of the operator is significantly reduced as the operator has to control only one of the first actuator 44, the second actuator 46, and the third actuator 48. Moreover, the operational cost for performing an operation has reduced significantly. Therefore, the present disclosure offers the skid steer loader 10 with the control system 12 that is simple, effective, easy to use, economical, and time-saving.

While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof. 

What is claimed is:
 1. A skid steer loader comprising: a frame; a linkage actuation system having a first arm connected to the frame, a second arm coupled to the first arm, and a work tool coupled to the second arm, the work tool adapted to contact with a work surface to perform an earth moving operation; and a control system for controlling a lift path of the work tool of the linkage actuation system, the control system comprising: a first actuator coupled between the frame and the first arm, the first actuator adapted to move the first arm about a first pivotal axis; a second actuator coupled between the first arm and the second arm, the second actuator adapted to move the second arm about a second pivotal axis; a third actuator coupled between the second arm and the work tool, the third actuator adapted to move the work tool about a third pivotal axis; and a controller in communication with the first actuator, the second actuator, and the third actuator, the controller adapted to receive an input from an operator, the input being indicative of a selection of the lift path, from a plurality of predefined lift paths, wherein the controller is adapted to control the actuation of two of the first actuator, the second actuator, and the third actuator for moving the work tool along the selected lift path. 